2 Answers
2

1000BASE-T (also known as IEEE 802.3ab) is a standard for gigabit
Ethernet over copper wiring.

Each 1000BASE-T network segment can be a maximum length of 100 meters
(328 feet), and must use Category 5 cable or better (including Cat 5e
and Cat 6).

So it's 100 meters (328 feet).

The network segment is not just the segment from one device to another, but must take account of the actual end-to-end delivery, for example device A - switch - device B. from A to B the 100m should be the cable length between device A to switch, plus the cable length between switch to device B.

It is incredible how the vendors want make you believe that only the cat6 is able to function in 1000Mbps at 100 meters.
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PaulocoghiMay 19 '12 at 16:35

But can you tell if the cat5e can run in full duplex at distances greater than 10 meters?
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PaulocoghiMay 19 '12 at 16:38

Sure Cat5e can run 1GbE full duplex for 10-30 meters. If it does not, it is a defective cable or a defective NIC.
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Dmitri ChubarovMay 19 '12 at 16:56

3

Why would the max run length have to take into account network switches? I thought that was only physical runs between, say, a switch and a client.
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TheLQMay 19 '12 at 17:33

5

Sorry but this is wrong, 100 meters are the length of the collision domain and not end to end. With a switch (very unlikely you are gonna see a Gbit HUB, and you would not be running full duplex over it anyway) it is 100 meters each endpoint to switch. You have to take patch panels, cables from wall jacks etc into account though!
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rackandbonemanMay 19 '12 at 21:22

Yes, this is wrong. I don't know what the maximum distance is but it has to do with the attenuation and interference that are inherent with a longer cable. The maximum distance is NOT affected by using a switch as the switch is in essence a "repeater". Once the signal reaches the switch, it is forwarded or "switched" to the line connected to whichever interface the outgoing signal will be sent on. Hence you could double the maximum length by using a switch in the middle. I came here trying to find the answer for myself, and felt compelled to point out the misinformation.

The recommended distance is, as far as I know a wire-length of 100 meters (or roughly 300 feet for the Americans that fought off British rule but are almost the only ones still using Imperial measures) before you need amplification (by a switch). For longer distances optical fibres are recommended.
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HBruijnFeb 3 at 23:08